W/Cu joining is key for the fabrication of high heat load components for fusion reactors, which however suffers from the low W/Cu bonding strength due to the immiscible nature of W-Cu system. In this study, we proposed a method for strengthened W/Cu joining based on femtosecond (fs) laser induced micron-scale W/Cu interface structure. W surfaces were irradiated by fs laser to form micron-scale cubes array, and then joined to Cu by hot pressing at 1000 °C, 80 MPa for 2.5 hours. The tensile strength of the W/Cu joining samples was investigated. The results show that micron-scale cubes array was successfully introduced into W/Cu interface without any cracks or pores. The interface structure helps to increase the W/Cu bonding strength to as high as 59.61 MPa, increased by about 50% as compared to W/Cu joining with a flat interface (bonding strength 40.11 MPa). The W/Cu bonding strength shows positive correlation with the W/Cu interface area, indicating the possibility to control the W/Cu bonding strength by simply adjusting the fs laser ablation parameters for the fabrication of cubes array on W surface. Our research provides a method for strengthened joining between intrinsically immiscible materials, including but not limited to W and Cu.